Nanomaterial-Based Electrochemical Sensing of Heavy Metals in Complex Food Matrices: Challenges from Material Design to Analytical Performance

Food contamination by heavy metals is a major threat to public safety, as these metals tend to bioaccumulate and can cause gastrointestinal, systemic, and neurological disorders. Consequently, there is an increased demand for precise yet accessible and low-cost detection of these hazardous metals in foods. Electrochemical nanosensors have been developed into highly sensitive analytical devices for detecting trace amounts of heavy metals in complex food systems. Recently, integrating nanostructured materials has become increasingly important, as it enhances electrochemical performance by increasing the active surface area, thereby improving electron-transfer kinetics and analyte adsorption at the electrode interface. This review highlights recent developments in nanomaterial-based electrochemical sensors for detecting heavy metals across a wide range of food matrices, including water and beverages, dairy products, seafood, fruits, and vegetables. Emphasis is placed on the use of carbon nanomaterials, metal and metal oxide nanostructures, and hybrid nanocomposites to enhance analytical sensitivity. A relative analysis of reported limits of detection indicates that nanostructured sensing platforms perform well for the analysis of trace levels of heavy metals in food systems. Furthermore, a thorough examination of emerging technologies, including flexible and wearable sensors, AI-assisted sensing, microfluidic approaches, paper-based sensing, and smartphone-integrated sensing, is also presented.